Standard Deviation Calculator
Sample and population spread, variance and standard error.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Sample standard deviation
- 2.160247
- Population standard deviation
- 2
- Sample variance
- 4.666667
- Mean
- 6
- Standard error of the mean
- 0.816497
Working
- 1n = 7, Σ(x − x̄)² = 28
Quick answer
Standard deviation measures average distance from the mean; sample SD divides by n−1, population SD by n.
s = √(Σ(x − x̄)² ÷ (n − 1))
How to use the Standard Deviation Calculator
- 1Paste your data separated by commas.
- 2Use sample SD for a sample, population SD for a full population.
- 3Read variance and standard error too.
Frequently asked questions
Why divide by n − 1?
Bessel's correction. A sample mean sits closer to its own data than the true mean, so dividing by n underestimates the spread.
What does one SD mean?
In a normal distribution, about 68% of values fall within one standard deviation of the mean.